What are volcanic hotspots?

Volcanoes are most common at plate boundaries, but some form in the middle of tectonic plates, far away from any boundary. Hotspots create these unusual volcanoes.

What is a hotspot?

A volcanic hotspot is an area where a column of very hot mantle rock, called a mantle plume, rises towards the Earth’s surface.
This heat melts the base of the lithosphere, causing magma to break through the crust and form volcanoes.

Hotspots can occur:

• beneath oceanic crust (e.g. Hawaii)
• beneath continental crust (e.g. Yellowstone, USA)

How do hotspots form volcanoes?

1. Hot mantle rock rises in a narrow plume.
2. The heat melts the crust above it.
3. Magma reaches the surface and forms a volcano.
4. As the tectonic plate slowly moves, the hotspot stays in the same place.
5. New volcanoes form above the plume, while older ones move away and become extinct.

This creates a chain of volcanoes, lined up in the direction the plate is moving.

Key features of hotspot volcanoes

• They produce runny, basaltic lava, similar to volcanoes at divergent boundaries.
• Eruptions tend to be frequent but less explosive.
• Over time, repeated eruptions can build shield volcanoes. wide volcanoes with gentle sides.
• Older volcanoes gradually sink below sea level, becoming seamounts.

Famous hotspot examples

Hawaii, Pacific Ocean

• One of the clearest examples of a hotspot.
• The Pacific Plate moves northwest over a stationary mantle plume.
• This has created a long chain of volcanic islands, including Hawaii, Maui and Oahu.
• The youngest volcanoes are directly above the hotspot; the oldest are furthest away and now extinct.

Yellowstone, USA

• A hotspot beneath continental crust.
• Heat and gases rise beneath the North American Plate, feeding geysers, hot springs and mud pools.
• Magma beneath Yellowstone has produced massive eruptions in the distant past.

Why are hotspots important in geography?

• They prove that not all volcanoes form at plate boundaries.
• They provide evidence for plate movement because the age of volcanoes increases as you move away from the hotspot.
• They help scientists track the speed and direction of plate motion.